In the jet engine and the turbine engine technical fields, there has been a constant endeavor to increase energy output per unit of fuel. Generally, in a gas turbine installation, a part of compressed air generated from a compressor is used for turbine cooling. Thus, an improvement in power efficiency and an increase in an output of a gas turbine system can be achieved by increasing the cooling capability of cooling air and reducing the amount of compressed air required for cooling. To that end, a technique for reducing the flow rate of compressed air required for cooling blades is practiced. A turbine blade cooling circuit is often used. However, the high pressure from the compressor makes it difficult for the turbine blade cooling circuit to operate in an ideal manner.
A gas turbine or jet engine typically includes a compressor assembly for compressing a working fluid, such as air. The compressed air is flowed into a combustor which heats the fluid causing it to expand. The expanded fluid is then forced through the turbine.
The output of known gas turbine engines is limited by an operating temperature of the working fluid at the output of the compressor assembly. At least some known turbine engines include compressor cooling devices, such as intercoolers, to extract heat from the compressed air to reduce the operating temperature of the flow exiting the compressor. As a result of the decreased temperatures, increased power output can be achieved by increasing flow through the compressor assembly.
To facilitate additional cooling, at least some gas turbine engines include water injection systems that overcome some of the shortcomings associated with intercoolers. Such systems use a plurality of nozzles to inject water into the flow during engine operation.
The essential goal in designing the jet engine has always been to produce more thrust and fuel efficiency to achieve turbine durability (that is, an improved component life). To do so, the combustor needs to operate at a higher temperature, which requires cooling the turbine. The first mass produced axial engine, Jumo 004B, utilized internal cooling for the turbine blades. So, the concept is as old as the turbojet engine itself. Fuel efficiency can further be enhanced by cooling the turbine blades with airflow or liquid-flow into gas (steam) through them. Afterburners provide a a means for an emergency boost; however, they suffer from fuel inefficiency relative to the other working components of the turbine.
FIG. 1 illustrates a conventional driven apparatus 100 that contains an engine and in particular, the apparatus 100 is in the form of an aircraft that includes a turbine engine 200. However, the present invention is not limited to being used in an aircraft and it will be appreciated that it equally can be used in other gas turbine settings including a vehicle, ship, electrical power generation, etc. As shown in FIG. 2, the turbine engine 200 includes a number of components some of which can be broadly categorized and identified as a compressor 300, a combustion chamber 400, a fuel burner 500, a turbine 600, and a nozzle 700. FIG. 2 illustrates one exemplary form of a turbine engine in the form of a jet engine, a turbojet, a gas turbine, a ramjet, or a scramjet engines; however, it will be appreciated that the turbine engine 200 can be of another engine type.
FIG. 2 illustrates an overview of the jet engine 200, wherein air 210 is drawn into the turbojet by the high by-pass fan 250 and the compressor 300. The compressor 300 is basically a large spinning fan. The compressor slows down the incoming air, raising its pressure, and delivers it to the combustion chamber 400. Fuel is injected into the high-pressure air in the combustion chamber and ignited by the fuel burner 500. The resulting hot gases 410 expand and rush first through the turbine 600 and then through the nozzle or exhaust section 700 located at the rear. A rotating shaft 800 may connect all the above components to provide momentum when rotating. A forward thrust is generated as a reaction to the rearward momentum of the exhaust gases.
The turbine 600 includes a series of bladed discs that act similar to a windmill, gaining energy from the hot gases 410 leaving the combustor. Some of this energy is used to drive the compressor, and in some turbine engines (i.e., turboprop, turboshaft or turbofan engines), energy is extracted by additional turbine discs and used to drive devices such as propellers, bypass fans, helicopter rotors or electrical generators. These series of bladed discs are known as turbine blades.
FIG. 3 illustrates various components of the turbine engine 200 showing detailed view of the turbine 600, including various blades 602 and 602a. The hot exhaust 410 acts on the turbine blades 602, while leaving the combustion chamber 400 causing the turbine blades to spin around. A forward thrust is generated as a reaction to the rearward momentum of the exhaust gases when the hot gasses 410 rush toward the blades leaving the nozzle (exhaust section) 700. The turbine 600 is designed to provide mechanical energy and rotation to the compressor.
The purpose of the turbine is to provide momentum to the compressor 300 that is attached by the rotating shaft 800, thereby enabling the compressor 300 to continually draw in more air. Thus, the air that is compressed in the compressor 300 and then heated in the combustion chamber 400 is not only used to provide a forward thrust but also to drive the turbine 600 that drives the compressor 300 that compresses the air.
The difficulty with making the exhaust gases drive a turbine 600 is that the forward thrust depends upon the difference in pressure between the closed and open ends of the combustion chamber 400, and if the escaping gases have to push against an object (e.g., the turbine blades) that difference in pressure is lessened. In other words, a pressure at the rear of the system detracts from the forward thrust. Thus, the designer's aim in a turbojet engine is to reduce to a minimum the power taken by the turbine 600 to compress the air so that the maximum amount of forward thrust is available.
Since the turbine blades 602a come into contact with the hot combustion gases, the blades 602a (especially the edges) get very hot, which adversely impacts the efficiency of the engine. It has been proposed to cool the blades by flowing air relative to the blades in order to cool the surface of the blades and thus increase blade efficiency. While decreasing the temperature of the blades can yield some improvement in efficiency, this arrangement can be improved upon in order to yield a more efficient arrangement.
There is thus a need for an improved, alternative design involving cooling ejection by dispersing liquid throughout the turbine area or on the turbine blades or the rotating shaft of the turbine. Further, there is a need to produce a unique jet engine turbine blade design where water or other liquid is introduced into the blade and then discharged from the blade as liquid droplets (e.g., 10 micron size) that contact hot combustion gases, thereby generating a gas (e.g., steam) and yielding combustion gas volume increase converting heat energy to thrust energy and/or mechanical energy. This energy can then be extracted by an aeroderived gas turbine power turbine unit. In at least some embodiments, the claimed arrangement is done to increase the thrust output of the turbine by heat energy that generates the gas and thereby increase the efficiency of the jet engines.